/**
 * 发送get请求
 * @param {string} url 请求地址
 * @param {object} params 请求参数
 * @param {string|undefined} type 返回的接口数据类型
 * @param {object} headers 自定义请求头
 * @returns Promise
 */
function get(url, params, type, headers = {}) {
    // 过滤数据
    let temp = []
    for (let key in params) {
        temp.push(`${key}=${params[key]}`)
    }
    let paramsFilter = temp.join('&')

    // 返回promise对象
    const p = new Promise((resolve, reject) => {
        const xhr = new XMLHttpRequest
        xhr.onreadystatechange = () => {
            if (xhr.readyState === 4) {
                if (xhr.status === 200) {
                    let res = xhr.responseText
                    if (type === 'json') res = JSON.parse(res)
                    resolve(res)
                } else {
                    reject(xhr.status)
                }
            }
        }
        xhr.open('get', `${url}?${paramsFilter}`)
        for (let key in headers) {
            xhr.setRequestHeader(key, headers[key])
        }
        xhr.send(null)
    })

    return p
}



// 开启loading
// get(url, params, type, headers={})
// .then()
// .catch()
// .finally(() => 隐藏loading)


/**
 * 发送post请求
 * @param {string} url 请求地址
 * @param {object} params 请求参数
 * @param {string|undefined} type 返回的接口数据类型
 * @param {object} headers 自定义请求头
 * @returns Promise
 */
function post(url, params, type, headers = {}) {
    // 过滤数据
    let temp = []
    for (let key in params) {
        temp.push(`${key}=${params[key]}`)
    }
    let paramsFilter = temp.join('&')

    // 返回promise对象
    const p = new Promise((resolve, reject) => {
        const xhr = new XMLHttpRequest
        xhr.onreadystatechange = () => {
            if (xhr.readyState === 4) {
                if (xhr.status === 200) {
                    let res = xhr.responseText
                    if (type === 'json') res = JSON.parse(res)
                    resolve(res)
                } else {
                    reject(xhr.status)
                }
            }
        }
        xhr.open('post', url)
        xhr.setRequestHeader('content-type', 'application/x-www-form-urlencoded')
        for (let key in headers) {
            xhr.setRequestHeader(key, headers[key])
        }
        xhr.send(paramsFilter)
    })

    return p
}

